The present invention relates to a handy phone or similar radio communication apparatus capable of controlling the volume of an alert tone and, more particularly, to a radio communication apparatus capable of reporting an unusual situation happened to the user of the apparatus to those around the user.
A value-added alert tone to be output on the receipt of a call is important with a handy phone, a slave unit included in a cordless telephone system, a mobile phone, a wireless microphone or similar radio communication apparatus. The value-added alert tone promotes the users's convenience as to the handling of the phone and allows the phone to adapt itself to the varying environment. Radio communication apparatuses with improved control over the alert tone are taught in, e.g., Japanese Patent Laid-Open Publication Nos. 4-56536 (document 1) and 63-187433 (document 2). However, the conventional value-added alert tone schemes have some problems left unsolved, as follows.
One of the conventional schemes measures a noise level around the apparatus, and then determines the volume of the alert tone matching the measured noise level. Although this kind of scheme successfully alerts the user to an incoming call in a noisy environment, it does not work when the alert tone must be loudened despite a quiet environment. For example, when the apparatus is put in the user's bag and buried in other various goods, it is likely that the user does not notice the alert tone. In such a case, the volume of the alert tone cannot be increased because the noise level in the bag is usually extremely low.
Another conventional scheme sequentially increases the alert tone with the elapse of time during a single call incoming from, e.g., a base station in a handy phone system, calling the user's attention little by little. However, the time when the caller gives up calling and hangs up depends on the person. If the caller calls the same apparatus repeatedly, but hangs up soon each time, then call incoming always fails before the alert tone of the apparatus is loudened. This practically prevents the apparatus from calling the user's attention.